The present invention relates to video display units that can stow and display a monitor.
Entertainment and information systems aboard aircraft have been made available to passengers for their comfort. Such systems can include television monitors that display movies and other programming, including safety instructions. Monitors can be stowed in the ceiling of the passenger cabin and are typically attached to a hinge allowing for rotational deployment from a cavity in the ceiling. An electric motor typically provides the power enabling rotational deployment, including retraction of the monitor when not in use. Electrical power necessary to deploy and retract the monitors comes from that generally available to the aircraft for use by the cabin during flight. It is therefore desirable to reduce power consumption to enhance efficient usage of on board systems.
In an emergency situation, deployed monitors can be a significant obstacle to both movement and line of sight for passengers. As such, where the aircraft cabin loses electrical power, Federal Aviation Administration regulations require that all monitors be retracted and stowed in a specific time frame of approximately five seconds. Where monitors were of a smaller size, i.e., approximately 8.4 to 9 inches, a battery or other stored power source within the monitor could suffice to automatically retract the monitors and comply with the FAA regulations, even though this extra power source constituted a further drain on energy needed to charge and maintain potency. Furthermore, this is less feasible for larger size screens, i.e., those 15 inches and larger, which required significantly greater rotational force to be generated in order to automatically retract them in the time period required. Additionally, these larger screens, with their greater power consumption for rotational motion, benefit from a more efficient source of rotational force. Torsion springs are the most common mechanism currently used for this purpose, but are not very efficient from a systems operation standpoint. This is due to the fact that less torque is required when the monitor is deployed than stowed which is opposite of the operation of torsion springs.
An apparatus is described which includes a frame, a video monitor display mounted to the frame, a torque shaft coupled to the frame such that rotation of the torque shaft causes the frame to pivot along a predetermined arc. The apparatus further involves engaging to the torque shaft to impart rotational motion to the torque shaft, a releasable cam follower slidably disposed on the cam shaft and a spring mounted on the cam shaft exerting a spring bias force directed toward the cam so as to cause rotational motion of the cam.